Photonic Crystal Attenuator with a Flexible Waveguide and Nano-Rods

We propose a mechanical tuning method for a two-dimensional photonic crystal (2D-PC) attenuator with a flexible waveguide and double-layered nano-rods. The 2D-PCs have a triangular lattice of air holes in a silicon slab waveguide. PCs act as optical attenuators because of their photonic band gaps. By inserting nano-rods (500 nm in diameter) into PC’s air holes (650 nm in diameter), the refractive index in the holes changes. Therefore transmittance can be tuned by insertion depth. We fabricated the device by an alignment-free simple process with direct EB lithography and demonstrated 7 dB attenuation at 1500 nm of incident wavelength.